Screw



Nov. 6, w23. ummm v E. GERZE'N SCREW Filed sent. 28 1922 maree nee. e,reas.

intacte 'VIK'KR MANUEL GERZN, @E SVANOBRUK, SWEDEN.

SCREW.

Application filed September 2e, 1922. Serial. No. 591,149.

T 0 al? 'wlw/m. t may cof/warn:

Be it known that l, Vm'ron EMANUEL GnnzN, a subject of the King ofSweden. residing at Svanobruk, in the Kingdom of Sweden, have inventedcertain new and useful Improvements in Screws, of which the following isa specification.

When using screws of that type, which are provided with a transversalslot in the head or the end, there are often some inconveniences. Thus,for instance, it is impossible, when screwing in the screw, to hold andguide the screw in a reliable manner by means of a screw-driver only. Afurther drawbackrconsists in the edges of the slot being worn off at thescrewing in and unscrewing of the screw, so that the screwdriver finallyglides out and the carrying out of the said operations is impossible.Besides, in order to prevent the screw-driver from gliding out acomparatively great pressure axially of the screw generally must beexerted, which, however, not always is possible.

ln order to remove the said drawbacks it has been proposed to provide inthe head or end of the screw a substantially central part, which islocated between two recesses and may be grasped by means of the jaws ofa tongs or the like. The present invention relates to screws of the typelast mentioned and the object of the same is to so arrange the saidcentral para-that it may be grasped by the tongs and the screw held in amore reliable 'manner than hitherto.

In the accompanying drawing Figs. 1 and 2 are two different side'viewsof a screw arranged in accordance with this invention. Fig. 3 is a planview of the screw. Fig. 4 is a longitudinal section of the screw andshows the ends of the jaws of a tongs used for screwing in andunscrewing the screw. Fig. 5 shows in a longitudinal section a screwwithn modified shape of 'the recesses. Figs. 6 and 7 are plan views ofscrew heads provided with recesses difi'erin from those shown in Fig. 3.Figs. 8 an Ve9 show details.

in the head l of the screw two slots or recesses 2, 2 are provided,between which there is a central part 3. The said part 3 is dove-tailed,as shown. 'The angles formed by the bottom sides of 'the recesses 2 and2 and the sides of the dove-tailed part 3 may,

evidently, be varied, as shown in Figs. 8

and 9. In the screw shown in Figs. 1 to liinclusive the recesses 2, 2are rectangular transversally and extend radially inwards from theperiphery of the head 1 to the central part 3. rlhe bottom walls of therecesses are substantially .perpendicular to the longitudinal axis ofthe screw. The width of the recesses and thus 'the length of the centralpart may, evidently, be varied and is adapted to the shape and the sizeof the screw, compare Figs. 3 and 6.

In Fig. 4 the jaws 4 of a tongs are indicated. rllhe said jaws are putinto the recesses 2 and 2 and brought 'to engage the part 3. rlhe saidjaws arcguided laterally by the side walls of the recesses, so that thejaws t0- gether serve as a screw-driver atthe same time as they engagethe central parts Owing to the fact that the central part is dovetailedthe tongs, the jaws of which are correspondingly shaped, as shown inFig. 4, will hold the screw in a very reliable manner and the guiding ofthe screw, while it is screwed in, is -considerably facilitated.

In the screw shown in Fig. 5 the bottom sides of the recesses 2 and 2are curve shaped in such manner, that the depth of the recesses isgreatest at or in the vicinity of the central part. f j,

'The jaws of the tongs must not necessarily be guided laterally by therecesses. shown in Fig. 7 the recesses 2 and 2 may be so arranged, thatthe central part 3 extends transversallyl of the head for the whole (orsubstantially the whole) width of the same, so that the said head has atransversal dovetailedv projection. The said form of execution of theinvention is preferred with respect to the wholesale manufacture of thescrews. The bottom walls of the recesses may be plane orsemi-cup-shaped, as shown.

ll claim:

1. A screw including a head having opposed recesses extending radiallyinwards from the periphery and leaving a substantially centraldove-tailed part between said tially diametrically across the wholesurl0 recesses having its narrow section locatedut face 0f 'f lle head.s the bottom of the recess. In tesjtlnlony whereof Ihavc affixed my 2, Ascrew in accordance with claim 1 signature 1n presence of two witnesses.5 wherein the recesses are deepest in the of the d0ve ta iled )gal-Ll 3.screw in accordance with claim 1 Witnesses: wherein the recesses are ofsuch a, width GmBG EUGEN 0LssoN,

that the dove-tailed part extends substan- NILs OLov LvGREN.

